1. Field of the Invention
The present invention relates of optical connectors, and in particular, to an optical connector whose structure accommodates in a housing an optical connector ferrule urged forward towards a butt connection by an urging means.
2. Description of the Related Art
Optical connector ferrules such as those stipulated by JIS C 5981 (Japanese Industrial Standards) have been proposed as optical connectors which switchably connect together optical fibers.
In addition, recently, in consideration of, for example, improving the connection operability of this optical connector ferrule, what are termed MPO connectors (connectors optical connectors whose structure accommodates a multi-core optical fiber connector ferrule stipulated, for example, by JIS C 5981 in a plastic housing) have been used widely.
FIG. 11 and FIG. 12 show this MPO connector. In FIG. 12, this MPO connector 1 is stipulated by Japan Industrial Standards, JIS C 5982, and the International Electronics Standards Committee, EEC publication 1754-7, and has a structure wherein an optical connector ferrule 2, whose end is PC (physical contact) polished as stipulated by JIS C 5981, etc., and a pin clamp 4, which clamps a guide pin 3 inserted into this optical connector ferrule 2 in the vicinity (FIG. 12, right side) of the back end of the optical connector ferrule 2, are supported within a sleeve-like housing 5, the back end of this housing 5 is supported within a sleeve-like coupling 6, and an abutment force generating coil spring 7 is accommodated by the coupling 6. The optical connector ferrule 2 can move forward and backward (left to right in FIG. 12) in the housing 5, the housing 5 is urged forward (to the left side in FIG. 12) by the housing spring 8 installed separately, and when the optical connector ferrule 2 in inserted into the MPO connector 1, if the housing 5 is in the end position of the MPO connector 1 and does not move with the optical connector ferrule 2, then the optical connector ferrule 2 is completely inserted into the housing 5. When the housing 5 is inserted into the optical connector adapter 10 (see FIG. 11), the jacks 15 formed on this optical connector adapter 10 engage detachably with the engagement part 9 of the housing 5 side surface, and thereby the inserted state of the MPO is maintained.
Reference numeral 11 in FIG. 12 is a boot, and from its back end, and the optical fiber 12 (in this figure, optical fiber ribbon cords stipulated by JIS C 6839, etc.), which can terminate in a butt connection due to the optical connector ferrule 2, is pulled out. The exposed ends of the optical fiber core of the optical fiber 12, which is an optical fiber ribbon cord, are terminated by the optical connector ferrule 2, and the cord part is anchored in the housing 5.
Reference numeral 13 in FIG. 12 is the interior cavity, and accommodates a coil spring 7 that this optical fiber passes through.
However, in the above-described MPO connector 1, a pair of MPO connectors 1 are butt connected only by insertion from both sides of the optical connector adapter 10, and good optical characteristics and connection operability are attained. But, for example, as shown by the line in FIG. 11, when the optical fiber 12 pulled out from the back end of one connected MPO connector 1 is being pulled, and a pulling force is applied in the sideways direction on the MPO connector 1 (what is termed xe2x80x98side pullxe2x80x99), there is the possibility that the connections will not be aligned and that the characteristics may deteriorate due to sideways pressure being applied to the optical connector ferrules 2, 2 in a connected state.
That is, when a pulling force is applied in a direction other than the axial direction of the MPO connector 1, for example, in the direction of the arrow A, to the MPO connector 1 shown in FIG. 11, this plastic MPO connector 1 may be slightly displaced due to the small gap which exists between the range of deformability of the connector itself and the optical connector adapter 10, or the small gap between the optical connector ferrule 2 side surface and the wall surface inside the housing 5. On the other hand, when side pull above a tolerance value is applied, as shown in the conceptual diagram of FIG. 13, because the optical connector ferrule 2 positioned in the housing 5 is displaced as a whole with the MPO connector 1, displacement of the pressure force on the optical connector ferrule 2 of the MPO connector 1, which is the counterpart optical connector ferrule 2 of this MPO connector 1, and misalignment are produced, and thus it is possible that the object of low connection loss cannot be attained. Specifically, at the butt connection between the optical connector ferrules 2, the PC (Physical Contact) polished ends of the optical fibers 12a (bare fibers) exposed at the junction end surface 2a of the optical connector ferrule 2 are precisely butt connected by a specified pressure force, and between the several xcexcm to several tens of xcexcm diameter cores of the optical fibers 12a there is optical coupling, but when a slight displacement of the optical connector ferrule 2 in the MPO connector 1 is produced because of small deformations, etc., due to side pull of the MPO connector 1, a bias in the pressure force between the optical fibers 12a and misalignment of the optical axis are produced, an ideal PC connection state cannot be maintained, and connection loss between the cores of the optical fiber 12a in the abutted state is increased, That is, there are cases in which PC connection is possible. In addition, precision in the positioning between the optical connector ferrules 2 can be obtained by the engagement between the guide pin 3 (see FIG. 11) and the guide pin holes on the counterpart optical connector ferrule 2, but when the side pressure applied to the optical connector ferrule 2 becomes large, the optical connector ferrule 2 and the guide pin 3 can be damaged and fail, and the precision of the positioning is lowered.
In consideration of this problem, as shown, for example, in FIG. 14, one countermeasure is to provide a large clearance 14 which permits a floating of the optical connector ferrule 2 in the housing of the MPO connector 1. In this case, the application to the optical connector ferrule 2 of the sideways pulling force applied to the MPO connector 1 due to displacement of the optical connector ferrule in the housing 5 can be largely avoided. However, presently, the support position of the optical connector ferrule 2 in the MPO connector 1 becomes unstable, and it is difficult to fit a guide pin 3 inserted into one optical connector ferrule 2 into the guide pin hole of the other optical connector ferrule 2, and thus there is the problem that the connection operation between optical connector ferrules 2 deteriorates, and no fundamental solution to this problem has been achieved.
In light of the above-described problems, it is the object of the present invention to provide an optical connector which:
a) can ensure connection operability by stably maintaining an optical connector ferrule in a specified position in a housing during the connection operation between optical connector ferrules by a positioning retaining part, and can stably and reliably obtain favorable optical connection characteristics such as the intended low connection loss by preventing production of misalignment between optical connection ferrules after completion of the connection even if an external force is applied sideways on the housing; and
b) prevents the external force applied in the sideways direction to the housing from being applied to the optical connector ferrule and maintaining stably and reliably the PC connection state between optical connector ferrules by permitting the rotation of the optical connector ferrule centered on a rotating bearing part and floating in the housing when the optical connector ferrule is inserted into the housing and a stop guard is released from a position retaining part.
Thus the present invention is characterized in an optical connector in which an optical connector ferrule that can terminate an optical fiber by a butt connection is stored in a sleeve-like housing so as to be able to move in a direction axial to this housing, and further, said optical connector ferrule is urged by an urging means in a direction towards the butt connection from one end of an opening in the axial direction of said housing, wherein: a stop guard, which is releasably accommodated and supported by a positioning support part furnished in this housing, projects from said optical connector ferrule; a ferrule accommodating hole, which accommodates said stop guard permitting floating due to clearance away from the butt connection direction by said positioning support part of said housing, is provided; said optical connector ferrule is positioned and supported by said stop guard being accommodated in said position supporting part when said optical connector ferrule is urged by said urging means and moves towards said butt connection; and the floating of said optical connector ferrule in said housing is permitted by said stop guard being released from said position supporting part when said optical connector ferrule resists the urging force of said urging means and is pressed away from said butt connection direction.
According to the optical connector of the present invention, the superior effect is achieved that during the connection operation between optical connector ferrules, the connection operability can be ensured because the optical connector ferrule is stably maintained at a certain position and in a certain direction due to the stop guard accommodated and retained in the position retaining part, and after the connection is completed, because a gap permitting only the floating of the optical connector ferrule is ensured, even if external force in the sideways direction in the housing is applied, misalignment between optical connector ferrules is prevented, and the intended optical connectability characteristics can be stably and reliably obtained.
Moreover, in the present invention, the optical connector ferrule can be used for either single or multiple cores, and in addition, the shape of the optical connector ferrule can be used for flat, round, or any other kind of optical fiber of shape.
In addition, a preferred structure is one wherein the opening part of said housing is a tapered opening part whose shape expands in a taper towards the butt connection direction, and in the vicinity of this tapered opening part, a projecting rotation support part which freely rotatably maintains said optical connector ferrule is disposed, and said optical connector which rotates centered on this rotation support part becomes freely rotatable within the range of said tapered opening part.
In this case, a superior effect is attained wherein when the optical connector ferrule is inserted into the housing and the stop guard is separated from the positioning bearing part, free rotation centered on the rotating support part of the optical connector ferrule within the range of the tapered opening part formed in the ferrule accommodation hole is permitted, and thus it is possible to prevent an external force applied sideways to the housing from being applied to the optical connector ferrule, and the connection state between optical connector ferrules can be stably and reliably supported.